KZ AR15/M4 Receiver Extension Buffer Tube Block

(23 reviews) Write a Review
1.00 LBS
  • Designed to aid in the assembly of lower receivers. Once the armorer has installed the buffer tube onto the lower; the buffer tube and lower receiver assembly can be slid into the duo rings at the 12, 3, 6 and 9 o’clock positions.

This allows the armorer to rotate the lower in 90 degree increments in the block simply by loosening the provided nylon screws, removing the lower, and sliding it back in at the desired orientation. 

The Reaction Block provides an ultra-stable platform for performing an array of lower receiver operations, as well as making the installation of the buffer retainer nut quick and easy. All while keeping both hands of the armorer free to work, saving both time and frustration.
  • KZ AR15/M4 Receiver Extension Buffer Tube Block
  • KZ AR15/M4 Receiver Extension Buffer Tube Block
  • KZ AR15/M4 Receiver Extension Buffer Tube Block
  • KZ AR15/M4 Receiver Extension Buffer Tube Block
  • KZ AR15/M4 Receiver Extension Buffer Tube Block
  • KZ AR15/M4 Receiver Extension Buffer Tube Block
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Frequently bought together:


The Kley-Zion Buffer Tube Buddy was designed for assembly and maintenance of the AR15/M4 lower receivers.


  • Will work with both mil-spec & commercial buffer tubes
  • Mounts receiver in 12, 3 , 6 or 9 o'clock positions
  • Two polymer screws firmly holds buffer tube in position.
  • Mounts in any vice
  • 6061 T6 Aluminum
  • Clear, Type II class III hard Anodized
  • Only, 3.5" wide, 6" tall
  • Lightweight only 11.6oz
  • Lifetime warranty
  • 100% Made In USA

WARNING This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to You must be 18+ years old to shop and or purchase on our website and 21+ to purchase Ammunition/Firearms. Check local laws before ordering as you certify you are of legal age and satisfy all federal, state, and local legal/regulatory requirements. There are NO returns or exchanges on armor, firearms, ammunition, PPE equipment. Ammo ships UPS ground to the lower 48 states.
We reserve the right to fix any critical errors.

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Additional Information

Product ID:
Armorer's Tools
Made In USA
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23 Reviews

  • 5
    Kley Zion buffer tube block

    Posted by Country Girl on 6th May 2022

    Made very well, fantastic tool.

  • 5

    Posted by Mike Tidwell on 29th Mar 2022

    This is a simple inexpensive tool.............that is worth its weight in gold. It makes torqueing a carbine receiver extension extremely easy.

  • 5
    Buffer tube block

    Posted by RonB on 7th Mar 2022

    This is a well made tool that is reasonably priced.

  • 5
    Buffer extension fixture

    Posted by Erdyalx on 14th Jan 2022

    Works beautifully

  • 5
    Receiver Extension Buffer Tube Block Experience

    Posted by Ted on 20th Jul 2021

    With this block in a solidly mounted vise, torquing the castle nut to 40 lb-ft of torque is no longer an episode of the Keystone Cops. It is now an easy, quick, single-person job. We have all been there, myself included. A mixture of vise pads to protect the tube/receiver and a helper (or two) to coordinate the job. This block makes the crazy stuff we did in the past a smooth and satisfying task. Block is solid. Two nylon thumbscrews deter the buffer tube from sliding in the block. I am very satisfied with this purchase. Wish I had it during my first build.

  • 5

    Posted by Carlos G. Santiago on 17th Jun 2021

    Great product! An absolute must for your AR build.

  • 5
    Well made

    Posted by JOSEPH F LEIGHTY on 29th Apr 2021

    I was looking for a receiver block to hold the buffer tube during installation and the only other one was always out of stock and way too expensive. Then I found this one and it is perfect for the application. cost is great and it works like a charm. It is well worth the cost for the convenience of helping with assembly. I'm sure I haven't discovered all the benefits yet but I'm sure it will become a highly used tool.

  • 5

    Posted by Unknown on 2nd Apr 2021

    I find this product to be great!!! It’s just what I needed for my project, and I highly recommend this to everyone!!!!! Thank you again Botach!!!!!!

  • 5
    Botach buffer tube vice

    Posted by Scott Dean on 2nd Mar 2021

    Great tool

  • 5
    Best vise grip for buffer tubes!

    Posted by Edgar Cervantes on 27th Feb 2021

    If your thinking about building your own at-15, do not pass this up, not all buffer tubes come with an anti rotation cut for the buffer detent no matter how cheap or expensive so if you don’t want to risk the tube rotating and the end plate messing up the threads when torquing 40 foot pounds please buy this, you will not regret it, screws are polymer and will not scratch your tube, just slide in easy and steady, also make sure you clamp down pretty good with your vise to avoid this tool from moving.

  • 5
    Excellent Quality

    Posted by Unknown on 23rd Dec 2020

    This is a well made tool that is essential for no fuss tightening of the castle nut. With some 0.012" aluminum sheet I cut two 0.75" x 3" strips, smoothed the edges and then bent each piece into the same curve as the buffer tube. Putting each strip between the buffer tube and the bench block gave a nice snug fit and protected the buffer tube finish from the inside edges of the bench block. This is not at all needed, as the block works perfectly otherwise. Shipped quickly as well.

  • 5
    KZ Receiver extension tool

    Posted by Bryan L on 30th Nov 2020

    Price, Quality, ease of use deserve 5 complaints! I’ve built 16 lowers so far and it does what its supposed to!

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